Vacuum-tube control



May 29, 1928.

A. A. OSWALD VACUUM TUBE CONTROL Filed March 15, 1924 2 Sheets-Sheet 1 May 29, 1928. 1,6711205 A. A. OSWALD VACUUM TUBE CONTROL Filed March 15, 1924 2 Sheets-Sheet 2 I l25 2.? L25 Ari/24W ,4. Gama/a fl 771 Patented May 29, 1928.

UNITED STATES PATENT OFFICE.

ARTHUR A. OSWALD, OF EAST ORANGE, NEW JERSEY, ASSIGNORTO WESTERN ELEC- TRIO COMPANY, INCORPORATED, OF NEW YORK N. Y., A. CORPORATION OF NEW YORK.

VACUUM-TUBE CONTROL.

Application filed March 15, 1924. Serial No 699,431.

This invention relates to alarm and protective circuits used in connection with high voltage amplifierand other similar systems wherein energy of such value is used that the failure of some part of the system may cause material damage to the tubes or other parts of the apparatus.

The present application is a continuation in part of applicants copending application, Serial No. 562,973, filed May 23, 1922.

An object of this invention is to provide power control for an amplifying system automatically actuated by the failure of some part of the system to operate properly.

An important feature of the invention comprises interlocked master control and power control circuits whereby the operation of the master control circuit will cause the power control circuit to function.

A further object is to provide for giving an indication whereby the attention of the operator is attracted by the failure of any part of the set to function properly.

A particular object is to prevent the damage to the vacuum tubes used in systems of this class which might otherwise result from abnormal conditions in some single tube or other part of the apparatus.

A system in which the features of the invention are embodied comprises a high power amplifying system inwliich the waves to be amplified pass through the several stages before reaching the final amplifying set. A high frequency wave is modulated in accordance with speech frequency waves. From the resultant modulated wave is se lected one side band; this side band is changed in frequency by means of another wave and the resultant waves passed through two stages of low power amplification to an amplifier of intermediate power. From this am lifier the waves pass to. a high power amp ifier, i. e. having a high frequency energy output of the order of 200 kilowatts, and are impressed upon an antenna from which they are radiated.

The invention comprises amaster control circuit interlocked with apower control circuit and having associated therewith an alarm circuit for attracting'the operatorsattention by giving a. sound signal upon the failure of anypart of the set to function properly. A plurality of relay operated contacts are connected in series in the master control circuit. \Vater-flow control devices are also included in this circuit. Inter-locked with the master control circuit is a power control circuit which governs the action of the main oil switch between the source of alternating current and the rectifier system. \Vhen this circuit is broken the oil switch opens, cutting off power from the rectifier system which supplies direct current to the plates of the amplifier tubes. The interlock ing device consists of a remote control quick release relay, the energization of which will close the power control circuit and the deenergization of which will break the power control circuit. This relay may be deenergized because of several conditions, namely, failure of grid polarizing voltage, failure of proper water flow through the tubes, excessive current supplied to the plates of any one of the amplifier tubes, excessive current supplied to the plates of any one of the rectifier tubes, excessive voltage applied to parts ofthe rectifying system, and abnormal voltage applied to the direct current bus bar.

The novel features of the invention will 7 be readily apparent by reference to follow ing description read in conjunction with the attached drawings in which- Fig. 1 represents a schematic circuit arrangement of a transmitting system employing high power amplifiers in connection with which the present invention is used.

Fig. 2 reperesents the arrangement of the plate circuits of the amplifier tubes, each circuit having included therein a relay which operates when the space current supplied to that tube reaches a predetermined value above normal, the operation of which relay breaks a contact in the master control circuit.

Fig. 3 is a diagram of the master control circuit having interlocked therewith the power control circuit and the associated indicating or sound signal circuit.

- based on 60 kilocycles.

@n Fig. 1, circuit including microphone '11 represents a source of speech frequency which produces one side band in the output circuit of modulator 14 having a frequency This side band is selected by filter 15 and successively amplified by tandem connected amplifiers 16 and 17. The filaments of devices 12, 14, 16 and 17 are heated by current from the source 18. Theamplifiers 16 and 17 may be of any well known type, such as that disclosed in the patent to Scriven 1,415,417, June 19, 1923, and the modulators 12 and 14 may be of a type similar to that disclosed in Carson Patent 1,343,307, June 15, 1920. Filters 13 and 15 are of the type described in Campbell Patent 1,227,113, May 22, 1917. Waves from amplifier 17 are impressed upon amplifying system 19 which comprises a plurality of vacuum tubes and has a power output of intermediate value, for example, 15 kilowatts. Amplifier system 19 feeds into a high power amplifying system 20, comprising a plurality of high power water-cooled space discharge tubes, which in turn supplies signal modulated waves to the aerial 22 through the tuned circuit 21. The anode circuits of the amplifying systems 19 and are supplied with direct current from the rectifying system 23 which is supplied with three-phase alternating current from the source 24.

. Fig 2 represents a circuit diagram of the amplifier 20 of Fig. 1. Waves to be amplified from the source are impressed upon the grids of tubes 31 through the transformer 32, which may. have an iron core under certain conditions, and circuit 33, comprising inductance 34 and resistance 35. Negative potential is impressed upon the grids of tubes 31 from the source 89 (Fig. 3), the positive side of which is grounded.

The filaments of tubes 31 are heated by current from source 37 7 through the n'etwork 38 which is grounded at its mid-POlllt. Each filament circuit hasincluded therein a resistance 39 which controls the value of the current supplied tothe filament, The plates are supplied with current through a common bus bar connected to the output side of a rectifier 23 which in turn is supplied with alternating current by a source 24. Rectlfied current from the bus bar 45 passes through relay 7 and the circuit comprising resistance 41- and inductance 42 to the plate of each of the tubes. Resistance 41 and inductance 42 together offer resistive impedance to the fiow of undesired high frequency current while inductance 42 provides a low impedance path for the high frequency waves to be amplified. The combination of the two-in each plate circuit tends to reduce singing. Their effect is two fold, first to reduce the frequency at which singing tends to take place which has the effect of reducing the tendency of the circuit to sing and second, to increase the-damping to a point at which oscillations will not be supported. A capacity 43 which provides a low impedance path for waves of high frequency and a high impedance to rectifiedcurrent is shunted acrossthe relay 7, there by. causing the rectified current to How through the relays to the plates. Interconnecting the plates of the amplifier tubes is a path including resistances 44 which serve to assist in suppressing undesired'high frequency oscillations. These resistances make it possible for the same potential to be impressed upon the plates of each discharge.

' device. The'relays 7 do. not pick up their .armatures 52 on normal space current but are so adjusted as to pick up only on current of some predetermined value above normal.' When armature 52 is operated, a spring or gravity operated element 53 moves against a small projecting lever 54 pivotedon shaft 55. Inspection of the elements 53 indicates which tube has failed. The element 53 when released rotates the shaft 55 sufficiently to cause a projecting arm 56 to break the contact at 40, the relation of which to the master control circuit is shown in Fig. 3. Fig.- 3 is a schematic representation of the alarm circuit embodying this invention and used in connection with the system shown in i Fig. 1. As in Fig. 2, three phase current to be rectified is fed to the rectifying system 23, a part of which is shown, from the source 24. Oil switch'GO in the circuit con trols the connection of the power source to the rectifier. In two of the leads of the three-phase source are connected current transformers 61 and-62 which are adapted to operate relays 63 and 64 respectively.

The armature's of these relays are so arof relay 68. Rectifier system 23 is equipped with a plurality of horn gap arresters 70, to

prevent excess voltages on the line being supplied to the rectifiers. Resistance 71 is located in each horn gap circuit to determine the value of the current which is supplied to relay 72 when any gap sparks over. Capacity 73 is shunted across the relay 72 which is grounded. Relay 72 when energized, which happens when any one of the gaps sparks over, picks up its armature and breaks contact 7 4 included in the master control circuit. Thecircuit of each space discharge tubein the rectifying system 23 is supplied with a relay circuit-breaker 84, some of which are shown, to prevent the supply of excessive current to the plates of the tubes. Rectifier! current from the rectitier system passes through the iron core choke coil-75 and inductance 76 which tend to prevent singing in the circuits of the ampliliers 19 and 20. A lead connects points 78, which may be grounded, to the bus bar 77 carrying the rectified current. Switch arm 116 is constructed of metallic conductive material with a conductive band 117,, insulated from the arm. Bus bar 77 is provided with a horn gap 7 9 and grounded relay 80 which picks up its armature and breaks the master control circuit when abnormal voltage on the bus 77 causes the gap 79 to spark over. Re-

sistance 81 in the relay circuit limits the current which flows to the relay. The plates of the two tubesof the amplifier 19 are connected to relays 82 and 83 individually and the contacts made by these relays in the master control circuit are connected in series. The e relays are so wound that they do not pick up their armatures when normal current flows through the plate circuits but do so on overload, thereby opening contacts in the master, control circuit. Relay operated circuit breakers for the amplilicr 20 have been described with reference to Fig. 2 and their position in the master control circuit is shown by arms 56 and contacts 40. Relay. 85 is a slow release relay. It must be restored to position in which its armature makes contact with the power control circuit manually, being held in that position by normal voltage in the master control circuit. Relay 86 is a remote control contactor which picks up its armature and closes the power control circuit when current above normal flows through the master control circuit but is held in that position by normal voltage. Where no voltage passes through the master control circuit, the contact made by armature of relay 86 opens at high speed. The contacts of the relays 85 and 86 are in series in the power control circuit. Negative potential for the grids of the tubes of the amplifiers 19 and 20 is supplied by the motor generator set 89 through a lead 120 which extends from the negative terminal of the source 89 (Fig. 3) the potentiometer 131 (Fig. 2) and grid. circuit filter 132, through the input resistance 35 of the grids of tubes 31. The positive side of the generator is also grounded through one terminal of the switch 91. Condensers 90 are shunted across the grid polarizing generator 89 to shunt ed to ground any high frequency voltages picked up by the generator comiections. The amplifier 19 is supplied with grid potential from the source 89 by circuit connections (not shown) similar to those connected to the input circuit of the amplifier 20.

, A horn gap 123 is connected between the negative terminal of the grid generator and ground. In series with the gap 123 is a resistance 1:24 and a relay winding lifi'having its armature in series in the control circuit and normally closed. It the horn gap 123 breaks down. the relay 125 picks up its armature and opens the control circuit.

Resistances 92 and 93 are placed in the alarm circuit to regulate flow of current through the circuit. Resistance 93 can be shunted out of the circuit by master control push button 94 thereby allowing current above normal to pass through the circuit. Contact devices 96, 97 98 and 99 are controlled by water flow devices such as that shown at 95. When water flows at the desired rate in a tube cooling system, water flow device 95 causes contact device 96 to rotate in a counter-cloclm'ise direction to break the upper contacts and close the lower. When the rate of flow of water through the cooling system falls below a safe value the control device rotates in a clock-wise direction closing the upper contacts and breaking the lower. Device 95 is actuated by the water flowing through the tubes of amplifier 19, devices 97 and 98 by the flow through the two sets of tubes which make up amplifier 20 and the device 99 by the flow through the, tubes of the rectifying system 23. Ourrent for-heating the filaments of the amplifier tubes is supplied from an alternating current power line 100 through the switch 101 and the four pole switch 102. A transformer 103 is'connected across one phase of the alternating current circuit to supply current for the lights 106, 107 and 108 and to the transformer .105 which supplies energizing current. to the sound signal dcvice104. For operating in noisy surromidings the horn 104 may be a loud sounding device such as an automobile horn. A variable resistance is connected in each light circuit to limit the flow of current. The lamps are connected in parallel with each other, having the transformer in Series with the line so that the operation of any one of the lights will cause the horn to sound. A lead from the source cf alternating current 100 goes to the motor generator set 109. The output of the generator passes through fourtubes.

it is possible to run the rectifier for test or other purposes independent of the a nplify ing system and at the same time to have the rectifier tubes protected by the master control circuit and the alarm or-lamp lighting circuit. l/Vhen grounded relay 111 is energized its armature closes a circuit from ground through the resistance 112 and relay 113, which may be connected-to any point on the resistance 114, to ground. Relay 113 by picking up its armature closes acircuit which causes lamp 106 to be lighted and the horn 104 to sound. The clockwise rotation of any one of the contact devices 96, 97, 98 and 99 will close a circuit through the upper contact of that device and cause a lamp 107 to be lighted and the born to sound. At differentpoints in the cooling-system thermometers 115 are located. When the temperature of the cooling water reaches a predetermined danger point a circuit is closed from ground through the thermometer effected, through the secondary of transformer 119, the primary of which is supplied with alternating current from the three phase source, through the relay 118 to ground. When the left hand armature of relay 118 picks up a circuit is closed which lights a lamp 108 and causes the horn 104 to be sounded. When the right hand armature of the relay 118 picks up the master control circuit is opened.

0peratz'0n.To put the radio telephone amplifying set in operating condition a definite procedure must be followed. The water flow to cool the plates ofcthe amplifier and rectifier tubes is turned on, causing the control'devi'ces 96,97, 98' and 99 to be rotated in a counter-clockwise direction, opening the upper contacts vand closing the lower. Current to heat the-filaments of the amplifier and rectifier tubes is then turnedon by closing switches 101, 102and-110. Simultaneously,-the alarm circuit, including the'horn 104 and the lamps 106, 107, and 108, is supplied with current-by means of transformer 103. All the circuit breakers in the control circuit must be closed. After any breakvin the master control circuit these contacts must be restored to put the circuit in operating condition; For operating, the contacts made by the armatures of relays 111 and 113 should be opened; one of contacts made by relay 118 should be opened and the other closed, as shown; :those of relays 84,

72, 80,82, 83 and 85 should be closed, and y be closed by the perator. Relay 86 between the master control circuit and the power control system. Contacts 40 must be closed. The ground connection is then removed from direct current bus 77 at the point 7 8' by means of the switch 116. At the same time the power control circuit is closed by means of contact 117.

When the alarm circuit has been put in operative condition, motor generator 89 is started and switch 91 closed. The motor generator 89 supplies negative potential to the grids of the amplifier tube and also supplies current to the master control circuit. The path of current through this circuit may be traced as follows: From switch 91 through the resistances 92 and 93, lower contacts of control devices 96, 97, 98 and 99, contacts made by one of armatures of relay 118, contacts made by the armatures of relays 84 and 72, contacts 40, contacts made by the armatures of relays 80, 82 and 83 and through relays 85 and 86 to ground. To put the power control circuit in operative condition relay 86 must pick up its armature and, since the passage of more than normal current through the alarm circuit is required to actuate the relay, resistance 93 is shunted from-the line by the master control push button 94, longenough to cause the relay to pick up its armature.

Should there be no water flow through any set of tubes, lower contactsof the control device for that set would be'opened, upper contacts would be closed, lamp 107 lighted and horn 104 sounded. This would indicate to the operator the nature of the trouble and the point at which it is located. Should the water be flowing properly but one of the relay operated contacts opened,

the currentin the master controlcircuit would pass through the lowercoijtacts of the control devices 96, 97, 9 8"and 9'9, through contact made by onfe of thearmatures of relay 118,andthrough relay 111to ground. The armature of relay 111 will close a circuit from ground through resistance 112,

"through the relay 113- and to, ground throughresistance 114. The relay 113 in picking up its armature closes a circuit which lights lamp 106 and causes horn 104 to be sounded thereby attracting the operators attention and indicating what part of the circuit is affected.

After the tubes have been supplied with filament heating current, the grids with negative potential and the master control circuit isin operative condition, power may be supplied to the rectifiers from source 24.

Switch 69 is turned to the middle contact.

allowing current to flow from one side of the source of direct current 66 through" the contacts-.made by the armature of relay 65,

through the .make-before-break' swit h 69;

bank of lamps 67 holding coil 68, contact band 117, contacts made by armatures of relays 86 and 85 to the opposite side of the source of direct current (30. 69 is then thrown to the right, shorting out the lamps 67 and allowing full current to pass through the holding coil 68 which picks up its armature thereby closing the oil switch 60. As soon as the oil switch is closed switch 69 is thrown back to the mid dle position by springs 69, placing the lamps in series with the holding coil. Once closed, the coil 68 will hold the switch 60 closed on normal current in the power control circuit. Lamps 8 and 9 indicate the position of the armature of coil 68.

lVhile the set is working a number of causes will throw off the power.

Should excessive current be traversing, the rectifier from source '24 either of the current transformers 61 or 62 will energize a relay associated with it, that relay in turn causing contacts to be made whereby relay 65 is energized and the circuit to the holding coil 68 opened Coil 68 on being deenergized, allows its armature to drop, opening oil switch 60 and shutting oil' the power to the rectifiers. This trouble would be indicated by the lamp 9 being lighted. Should the plate of any one of the rectifier tubes receive excessive current, corresponding relay 81 would be energized, breaking the master control circuit at that point. Quick release relay 86 and slow release relay 85 would be deenergized breaking the power control circuitwhich' causes the relay 68 to be deenergized and-the oil switch 60 to open. At the same time lamp 106 would be lighted and the horn sounded in the manner explained before. By noting which relayhad ope1- ated the trouble could be quickly attended to. Should any part of the rectifying sys tem receive excessive voltage the corresponding horn gap would spark over, energizing relay 72, breaking the master control circuit at contact 74 and affecting the two associated circuits in the manner explained in connection with relays 84. Excessive current to the'plates of any of the tubes of amplifier 20 will cause the associated relay 7 (Fig. 2) to be energized, breaking the corresponding contact 40 and atl'ecting the two interlocked circuits in the same manner.-

Excessive plate current in any one of the tubes of amplifier 19 would cause relay 82 or 83 to be energized breaking the master control circuit andhaving the effect of shutting down the system. The horn gap 791s so constructed that it will spark over at surges of abnormal voltage onthe direct current bus 77, causing relay to be energized, breaking the alarm circuit and shutt ng off power to the rectifier. The power is shut oil when the'grid voltage supply fails because the control circuit then becomes de- The switch energized. By the arrangement of relays 85 and 86 the master control circuit is interlocked with the power control circuit. Thus any abnormal condition in the amplifying system or in the rectifying system which opens the master control circuit will take the power off the rectifying system. Should the temperature of the water used to cool the tubes reach too high a point, the thermometer 115 would close a circuit from ground through the thermometer 115, through the secondary of transformer 119 and the relay 118 to ground. Relay 118, in picking up its left hand armature closes a circuit, lights the lamp 108 and attracts the operators attention by causing the horn 104 to sound and by picking up the right hand armature the master control circuit is opened. Push buttons 25 are provided at convenient points about the set. When operated, any if them will ground the master control circuit causing relay 86 to operate which in turn opens the oil switch 60 without sounding the horn 10 1.

The rectifier 23 may be run independently of the amplifying system for test purposes by closing the switches 101 and 110 but leaving switch 102 open. The master control circuit would then be in operative condition as described above. It can readily be seen that the combination of the lights 106, 107 and 108 and the horn 101 is not necessary for the successful operation of the system. Either the lights, or the horn may be used independently of the other without impairing the working of the system. Any one of the protective devices included in the alarm circuit maybe used exclusive of any others and the circuit will function properly when comprising only a part of the devices herein described. Furthermore other protective devices may be added to those shown. It can be seen that the relay 118 may be provided with only one armature, which will cause the lamp to be lighted and that the thermometer can be so adjusted as to make contact at a temperature not dangerous. The operator could then control the water supply manually to lower the temperature without shutting down the set.

The present invention is'not limited to the arrangement illustrated, but may be embodied in other constructions within the scope of the following claims:

What is claimed is z.

1. In a'high voltage system including a plurality of fluid cooled, space discharge repeater devices, a source of power therefor, a power cut-ofi device, and means for operating said power cut-off device upon the occurrence of any of the following conditions: (a) failure of the grid polarizing supply; (b) reduction below the desired minimum rate of flow of the cooling fluid; (c) heating of the cooling fluid above a predetermined maximum temperature; ((1) rise above a predetermined maximum of the space current of any discharge device in the system; 5 (e) excessive voltage on the direct current bus bar; (f) abnormal voltage conditions in parts of the rectifying system which supplies the operating current, and (g) operation of any one of a'plurality of shut down switches distributed at strategic points about the system.

2. In a system in accordance with claim 1,

a master control element for restoring the power supply of the system, and means for preventing-the master control element from efl'ecting its function until the element causing the power cut-01f has been restored to the normal operating condition. I 3.- In a system in accordance with claim 1, means for attracting the attention of the operator, comprising a sound signal so associated with the control circuit that the occurrence of any one or moreof the conditions causing power cut-ofl will cause said signal to operate.

7 device having a cathode, an anode and a grid, means for supplying space current thereto, means for supplying grid biasing potential thereto, and means operated by the failure ofthe biasing potential supply means for cutting olfthe space current.

5. A high voltage 'system of space discharge devices comprising means for supplying to the .devices current of such a potential as to be dangerous to approach, nelay operated trips individual to, and adjacent to said devices actuated by excessive current, an element operated by the actuarent holding, high current pick-up relay held in one position by a control circuit, said relay when not so held functioning to operate said circuit breaker, means for. deenergizing said control circuit to release said relay, and'means for insuring. that momentary release of said relay will operate said circuit breaker, said last mentioned means comprising a resistance in said control circuit of such value, that except when it is short-circuited by a master control element, the current in said control circuit will be in 'suflicient to cause said relay to-pick up.

'7. In a high voltage high power amplifier system including a plurality of space disa charge devices, a circulating system for supplying cooling fluid to the anodes of said de- 4.1a combination, an electric discharge tion of any one of av plurality of said trips vices, an open alarm circuit, and means to complete said alarm circuit operated by a risein temperature, above a predetermined maximum, of the coolingfluid out-flowing in said circulating system. v

8. In a high voltage, high power, fluid cooled amplifier system having a filament heating circuit, an alarm circuit energized by the filament heating circuit of the system, and means controlled by proper flow of cooling fluid through said system for holding said alarm circuit ineflective to give an alarm.

9. A high power system comprising a lurality of space discharge devices, a p ate circuit and a current supply therefor, a circulating system supplying cooling fluid to the plates of said deviees, and means actuated by a rise in temperature, above a re determined maximum, of the fluid out owing in said circulating system for cutting 611' said plate current supply.

10.In a high power vacuum tube repeater system havin plate circuits, and a rectifying system, fied by a source of alternating current, for supplying space current to the plate circuits, a master control circuit for said repeater system interlocked with a power control circuit for said rectifying system and having associated therewith an alarm circuit for indicating the opening of the master control circuit, and means where-j by the opening of said master control circuit causes said interlocked power control circuit to be opened and causes the power supply to said rectifying system to be cut off.

11. In" a high voltage liigh power, fiuid cooled amplifier system having a filament heating circuit, anopen alarm circuit associated with the filament heatin circuit of the system, and means control ed by improper temperature of outflowing cooling fluid of the system to complete said alarm circuit. v

12. In a system in accordance with the preceding claim, means controlled by undesired space current in the plate circuits of the system forcompleting said alarm ci'rcuit.

13. In a high voltage, high power, fluid 115 cooled amplifier system havin plate circuits supplied with space current rom a rectify-' ing system by means of a common bus bar, a filament heating circuit, an alarm circuit adapted to be energized by the filament heat- 120 ing circuit of the system, and means controlled b undesired voltage in said common vbusbar or causing the energization of said alarm circuit.

14. In a system in accordance with the 125 preceding claim, means controlled b undesired flow of current in said rectifymg system for causing the energization of said alarm circuit.

15. A high power, high voltage vacuum 13 1 tubes supplied with space current by a. common rectifying system, gaps associated with said rectifying system, a master control circuit for said vacuum tube system interlocked with a power control circuit for said rectifying system, means whereby the sparking over of one or more of the gaps associated with said rectifying system causes a contact to be broken in said master control circuit, and means whereby the breaking of a contact in said master control circuit causes 'power to be cut oil from the entire system.

In witness whereof, I hereunto subscribe my name this 7th day of March, A. D., 1924.

ARTHUR A. OSWALD. 

